1. Field of the Invention
The present invention relates to a sheet feeder and an image forming apparatus.
2. Discussion of the Background
As conventionally known, image forming apparatuses include a sheet feeder that stores stacked recording media used for image forming. The sheet feeder is removable from a main body of the image forming apparatus to be refilled with recording media to be stored. The image forming apparatus further includes a feeding mechanism in the main body that stores the sheet feeder. The feeding mechanism separates the recording media stacked in the sheet feeder into individual sheet and feeds the sheet. The feeding mechanism includes a pick-up roller, a sheet feed roller, and a separation member (such as a separation pad and a separation roller). The pick-up roller comes into contact with the uppermost surface of the recording media stacked on the sheet feeder, and picks up an upper part of the recording media. The sheet feed roller and the separation member separate the part of the recording media picked up by the pick-up roller into individual sheets.
With the image forming apparatus including the feeding mechanism in the main body, when the sheet feeder is pulled out of the image forming apparatus, the uppermost recording medium might get caught by the feeding mechanism. As a result, the recording medium might flow over the sheet feeder to fall within and remain in the main body (sheet might remain in the main body). When the sheet feeder is inserted to the main body with the sheet remaining in the main body, the remaining sheet not only is damaged but also causes paper jam. In an attempt to prevent the sheet remaining problem. Japanese Unexamined Patent Application Publication No. 2009-203064 discloses an image forming apparatus that includes a pressing mechanism in the main body. The pressing mechanism presses the uppermost recording medium in the sheet feeder from above as the sheet feeder is being pulled out.
Unfortunately, the pressing mechanism disclosed in Japanese Unexamined Patent Application Publication No. 2009-203064 has such a structure that makes the pressing mechanism operate in tandem to the operation of pulling out the sheet feeder. Specifically, the operation of pressing the uppermost recording medium in the sheet feeder proceeds in proportion to the amount of pulling of the sheet feeder. This causes a time lag between the starting of the pulling of the sheet feeder and the finishing of the pressing of the uppermost recording medium by the pressing mechanism. Thus, there still remains a possibility that the uppermost recording medium flows over the sheet feeder in the time lag, leaving room for improvement in terms of reliability of restriction of the remaining of a sheet.
The present invention has been made in view of the above-described circumstances.